Efficient secure matrix multiplication over LWE-based homomorphic encryption

Dung Hoang Duong, Pradeep Kumar Mishra, Masaya Yasuda

Abstract


Homomorphic encryption enables various calculations while preserving
the data confidentiality. In this paper, we apply the somewhat homomorphic
encryption scheme proposed by Brakerski and Vaikuntanathan
(CRYPTO 2011) to secure matrix multiplication between two matrices. To reduce both the
ciphertext size and the computation cost, we propose a new method to pack a matrix into any single ciphertexts so that it also enables efficient matrix multiplication
over the packed ciphertexts. Our packing method generalizes Yasuda et
al.’s methods (Security Comm. Networks 2015 and ACISP 2015), which are for
secure inner product. We also implement our methods and give a comparison with
previous packing methods.

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DOI: https://doi.org/10.2478/tatra.v67i0.452